I own both but I barely use my DS although there are great games for it.

Castlevania, Mario Kart, New Super Mario Bros. Zelda, FF3.. etc. Also some games work great with the stylus, not to mention it has a better battery life than the PSP and Nintendo products have always held up better than Sony stuff. Add on to that it cost less than the PSP.

As for the PSP, pretty much recently great games have been coming out. FFT, Disgae, Jeanne D'Arc, Castlevania. More good games coming out soon, but I would say the best thing about it is wide range of capablities it has.

Custom Firmware allows for a ton of customization, pretty much like a desktop computer in addition to being able to play PSX games on it (I'm playing my "patch" version of FFT on it right now. PSP also plays music and vids although depending on what else you own you might not use it for that.

I personally use my PSP more but both are good choices and you really can't go wrong either way.

I truly would go with "Screw portable platforms", but since I'm only given two options, I think the PSP. Not only is its library actually starting to get good games, the graphics seem to be better on it. And while I do think dual screens on the DS is cool, the stylus is the bane of my existence.

Well PSP still has good titles other than ports like Metal Gear Solid, Silent Hill Origins, Monster Hunter, and upcoming Kingdom Hearts and Final Fantasy: Dissidia title.

Don't get me wrong though a lot of the good games out for PSP are pretty much ports of old games:

Disgaea - port of PS2 game with several additionsFFT - well you should know the changes with this gameTekken Dark Ressurection - great port of this fighting game, even if it is a port definitely worth taking a look at.Castlevania - Remake of Rondo of Blood for SNES and has the original Rondo of Blood which was only released in Japan as well as an updated port of SOTN (syphony of the night)

Most of the DS games are new stand alone games also the DS has backwards compatability with the GBA library which has a ton of great titles too.

Basically your choices are a somewhat fragile portable multimedia system with decent games but with many ports.

Or

A sturdy portable system focused on games with a good selection of good quality games, that use a sometimes quirky way of using the stylus, and also has the gba library behind it as well.

I'm pretty happy with my DS at the moment. I bought an R4 cart, allowing me to download and play any games I want for DS, GBC, GB, SNES, and NES. Might get the cart that also allows me to play GBA. It also doubles as a media center because of that, I can watch movies and the like too.

I do want a PSP sometime though, namely for my fave PS1 titles and FFT TWOTL and some other games like the Harvest Moon and Dissidia, but as a media center my DS is doing fine so far.

I LOVE my psp. It plays all my gba carts so well. Like, seriously, I own 4 gba's (used to work at a video game store, and I am a gamecube fanatic) and use none of them now that I have my customized psp. My recomendation, though, is to go find a 10 dollar ps2 joystick, I like the arsenal gamepads for this, and replace the psp dpad with it. Takes a little liquid cement, some good exacto knives, and a bit of patience, but the results are well worth it.

My vote goes to the DS. It has a bigger library of games to choose from and those game are actually good. The PSP has some good games but overall fails. If it wasn't for a few select games I really really wanted for the PSP, I wouldn't have gotten one.

It also has games like Phoenix Wright, and the new sequel to the 3 Phoenix Wright games, Apollo Justice. (lol @ the name Apollo Justice).

Note - The Phoenix Wright/Apollo Justice games are more like digitial storybooks for your DS rather a game, I mean there are things you can do but in general the game is fun because of the story and not because of the gameplay.

So if you ever wanted to play as a surgeon or a lawyer in a game, the DS is the console for you.